Face Unlock: How Does It Work and What to Watch out For

Face Unlock - CONTENTS

1. Why use Face Unlock?
2. How does Face Unlock work?
3. Is Face Unlock safe?
4. When use Face Unlock?

Why use Face Unlock?

You pick up the phone, it wakes up and unlocks itself before you even touch the screen. Face Unlock is quick, comfortable and it has a good level of security. When you use a PIN code, you may forget it sometime. Also, when you need to enter pin every time you use your phone, it becomes tiring over time. A huge advantage is that unlike fingerprint readers, Face Unlock still works in the cold or in the rain and wet or dirty fingers are not a problem either. But be aware that not all Face Unlocks work the same way, some of them are safer than others.

How does Face Unlock work?

The phone must first scan your face so that it can later recognize it when you unlock it. The process differs according to the type of the face reader, it use either two-dimensional or three-dimensional data:

Two-dimensional face unlock

The two-dimensional scan will take several photos of you face from different angles during the first set up. When signing in, if your phone recognizes that you match your saved face, it unlocks. If it finds significant differences, it will remain locked and you will need to enter the code. When unlocking the phone, the phone measures e.g. the width of the mouth and other parts of the face.

However, there are differences in 2D face unlock feature of different manufacturers and the phones themselves. Some phones use only ordinary photography to unlock, others use an infrared camera or ToF sensor. Some of them also take into account the fact that a person moves and from the video they are already able to work partly with a three-dimensional image. Security, speed, or reliability of the Face Unlock feature varies from phone to phone.

Three-dimensional face unlocking

A three-dimensional scan requires additional sensors, e.g. infrared projector, which creates a depth map of the user's face. It calculates how long it takes for the light from the camera to bounce off the face and return to the phone. The system then creates a 3D face model. Examination of the user's face is more detailed, and we can say that three-dimensional scanning is more secure than 2D scanning technology.

3D Face Unlock, which works well even in low light conditions, is used by iPhone 11 or iPhone 11 Pro ( Max ), but we can also find it in some android phones such as Google Pixel 4 .

Many manufacturers are also implementing their less known security methods - for example, Samsung Galaxy S9 has an iris scanner, but is hasn't been used for the next generations of their flagship phone.

Is face unlocking safe?

Face unlocking is considered a safe way to protect your phone's content, especially if it uses a 3D scan. Apple claims that with Touch ID (fingerprint unlock), the chance to unlock your phone with a random finger is 1: 50,000. But with Face ID (Face Unlock) the risk is significantly lower, 1: 1,000,000 - unless you have a completely identical twin. So if we decide to trust Apple, 3D Face Unlock is several times more secure than fingerprint readers.

For example, Pixel 4 also implements 3D Face Unlocking technology, but when the phone entered the market in 2019, its security technology could be easily bypassed - the user did not have to open their eyes to unlock, so the phone could be easily unlocked even when the person was asleep. This has been the subject of considerable criticism. Google therefore promised software update, which arrived on April 6, 2020. The update now adds an option that requires you to have your eyes open when unlocking. This option is now set as primary, but can be changed back to option which does not require open eyes.

2D Face Unlock also provides a high level of security, although we can't say this in general, as the technology differ from phone to phone. If you want to use this method of unlocking your phone and want to be sure of good security, also consider how effective it is in non-standard situations, such as unlocking with the eyes closed, in the dark, etc.

When use Face Unlock?

On Android, face unlocking technology can only be used to unlock your phone. On Apple mobile phone, it is possible to confirm payments on Apple Pay, purchases in the App Store and so on, in addition to unlocking the smartphone itself.

Face recognition is a popular way to unlock your phone beside fingerprint readers. Its advantages include security, simplicity and convenience, because you simply take the phone and it unlocks itself in a few tenths of a second. But be aware of the method which uses only a regular photo scanning - it is less reliable and easier to bypass. It is better to check the security level of a particular phone before purchasing it or focus directly on 3D technology and then on its reliability in as many situations as possible.